CVE-2019-9808 in Firefox
Summary
by MITRE
If WebRTC permission is requested from documents with data: or blob: URLs, the permission notifications do not properly display the originating domain. The notification states "Unknown origin" as the requestee, leading to user confusion about which site is asking for this permission. This vulnerability affects Firefox < 66.
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Analysis
by VulDB Data Team • 09/07/2023
This vulnerability in Firefox versions prior to 66 represents a significant security disclosure related to the WebRTC permission handling mechanism. The flaw occurs specifically when web applications request WebRTC permissions from documents that utilize data: or blob: URLs. These URL schemes are commonly used for embedding binary data directly within HTML documents or creating temporary file representations without requiring server-side resources. The vulnerability stems from improper origin validation and display logic within Firefox's permission notification system, where the browser fails to correctly identify and present the actual source domain of the permission request.
The technical implementation of this vulnerability involves the WebRTC permission API which allows websites to request access to user media devices such as cameras and microphones. When a document loaded via data: or blob: URLs attempts to request such permissions, Firefox's user interface component responsible for displaying permission prompts becomes confused about the origin identification process. The browser's security model relies on proper origin tracking to inform users about which domain is making the request, but this mechanism breaks down for these specific URL schemes. The resulting notification displays "Unknown origin" instead of the actual domain that initiated the request, creating a misleading user experience that could potentially be exploited in social engineering attacks.
The operational impact of this vulnerability extends beyond simple user confusion to potentially undermine the browser's security model and user trust. Users may unknowingly grant permission to malicious actors who craft deceptive WebRTC requests using data: or blob: URLs, as they cannot properly identify the requesting source. This issue affects the fundamental security principle of informed consent in web browsing, where users should be able to make educated decisions about granting permissions based on clear origin information. The vulnerability particularly impacts users who frequently interact with web applications that utilize these URL schemes for data processing or temporary file handling, making it a significant concern for privacy-conscious users and organizations that rely on Firefox for secure browsing operations.
Security researchers have classified this vulnerability under CWE-200, which deals with information exposure, as it exposes users to unclear origin information during permission requests. The issue also relates to CWE-352, which covers cross-site request forgery vulnerabilities, as the confused origin display could potentially be exploited to manipulate user decisions in permission granting. From an ATT&CK framework perspective, this vulnerability maps to technique T1059.007 for Web Shell usage and T1566 for phishing attacks, as it creates opportunities for attackers to craft more convincing deceptive permission requests. The vulnerability demonstrates a critical flaw in Firefox's permission UI implementation and highlights the importance of proper origin validation across all URL schemes. Organizations should prioritize updating Firefox installations to version 66 or later, where this vulnerability has been addressed through improved origin detection and display mechanisms. System administrators should also consider implementing additional security measures such as browser security policies and user education programs to mitigate potential exploitation risks while awaiting full patch deployment.